1. Technical Field
The present disclosure relates to radiofrequency ablation devices. More particularly, the present disclosure relates to radiofrequency ablation devices having an adjustable insertable length and/or an adjustable exposed length.
2. Background of Related Art
Radiofrequency ablation (RFA) is a therapy commonly used for the treatment of solid tumors in the liver and lung. Typically, devices configured for RFA are intended for coagulation of tissue during percutaneous, laparoscopic, and open surgical procedures. Such devices produce local tissue heating at the tip of an active electrode using radiofrequency current applied between the active electrode needle and grounding pads, resulting in a defined volume of tissue necrosis (also referred to as an ‘ablation’). Some of these devices include a system that circulates chilled water through the electrode to control the tissue impedance at the electrode surface, allowing for increased energy deposition into surrounding tissue. Once such system is provided in the Cool-Tip™ RF System E Series available from Covidien of Boulder, Colo.
Generally, the RFA devices are provided to a clinician with multiple active electrodes of various configurations. The electrodes are identifiable primarily by the overall length of the insertable portion of the electrode and the length of the exposed portion of the electrode through which RF energy is delivered to tissue. Providing electrodes of different lengths allows physicians to access a variety of locations within the body and in patients having different body habitus. For example, in obese patients, it is desirable to provide longer active electrodes, as the insertable portion must often pass through layers of subcutaneous fat that can commonly be 5″-6″ thick. Though a longer active electrode length (e.g., 25 cm) would be preferable for such patients, such a length would be unwieldy for thinner patients. Providing electrodes of different exposure lengths allows physicians to control the geometry of the ablation. A shorter exposure length (e.g., 7 mm) results in a shorter axis, smaller ablation, while a larger exposure length (e.g., 4 cm) results in a taller axis, larger ablation. The exposure effectively limits the amount of RF energy that can be delivered via the active electrode, much like a camera's aperture limits the amount of light that reaches the photographic film.
Numerous active electrodes are required to provide a clinician with an electrode having both the correct combination of desired insertable length and desired exposed length. Providing the numerous active electrodes of various lengths is costly, and since only a couple of the numerous active electrodes will likely be used during a procedure, providing numerous active electrodes is also wasteful.